Strapping or tying down a load is a common means of attempting to retain a load on an open bed vehicle. Typically, a cloth strap, ropes, flexible cord, or chain is used to wrap the load, depending on the application and the type of load. For purposes here, except as noted, a generic term "strap" has been adopted. As loads vary, the type of strap also varies. A heavier load will require a stronger strap. A small item may require only one tie down strap. A large item or numerous items including stacked items or other items in palletized units, require more straps or even chains for proper securing.
After the load is wrapped, it is necessary to tension the straps in order to keep the load from shifting. Various means of accomplishing this tension are well known in the prior art. The simplest is an attempt to tie off the tie down strap tightly. More complex devices include mechanical tensioning means. These operate in various ways which usually includes binding and pulling the strap whereby the strap is placed in tension.
Many problems result from this tensioning. The largest problem results from using cloth straps over heavy loads, in particular, lifts of steel. Many materials transported in this way have rough outer surfaces. Such surfaces have a tendency to cut into the straps, thereby reducing the integrity of the load. Sudden shifts in a load at this point could result in a load catastrophically falling from a vehicle bed thereby affecting the safety of any person or property nearby at the time. In addition, the goods being transported are either damaged or destroyed.
However, more likely is that the cloth strap which is cut does not completely sever. Instead, the cut results in loosening of the load due to stretch of the fabric material. As a consequence, the reduction of tension of the cloth strap results in the strap having the ability to slide across the load. The strap may slide off the load or alternatively, slide enough to allow the load to shift, resulting in damaged goods. In such shifting, the load can violently impact the strap. The impact can also lead to a severing of the strap resulting in the load falling from the vehicle bed, causing injury to person and property, and damaging the goods being transported.
Further, even when the load makes it safely to its destination, the cloth strap is cut and damaged. Therefore, cloth straps can only be used once before disposal is required. Attempts to repair a cut strap in a manner which preserves its strength have proved impractical and cost-prohibitive.
Chains have been used as tie-down straps in an attempt to overcome the inadequacies of cloth straps, and to provide added strength to prevent load shifting. However, chains, when securely tightened have a detrimental effect on the load itself. A chain tends to cut into the load on the vehicle bed, damaging, or in extreme situations, destroying the goods. This result has been seen even where the goods are lifts of steel or steel coil.
By cutting into the surface, the tension in the chain is further reduced, allowing the load to shift, which creates and further perpetuates damage. Additionally, any time a load is allowed to shift, the possibility of failure of a chain or tie down strap increases dramatically.
Prior attempts to protect the load from the cutting of a strap or to protect the strap from damage have not been successful. These prior attempts included blocks of wood and rags placed at a load corner which would tend to slide out from under the strap. In addition, the device falls off the load in transport and is lost. This prevents re-use and creates safety hazards on the roadway.
Prior art strap corners also do not remain in place. They tend to slide out f rom under the strap. This sliding effects the tension in the strap. If a strap corner slides on the load while the tie-down strap remains in contact with the strap corner, the strap stretches. If the strap returns to its original position, tension in the strap is now reduced, and the load is allowed to shift. If, instead, the strap corner slides out from under the tie down strap, a void is created between the load and the strap. The resulting reduction in tension in the strap allows the load to shift , creating all of the inherent problems associated with load shifting.
Secondly, if a strap corner slides loose from between the strap and the load, it usually does so in transport and becomes lost. As discussed hereinabove, strap corners will normally experience some sliding along the load due to load shifting and stretching of the strap. The resulting loss in tension of the strap can result in the strap corner sliding out from between the load and the strap. This typically results in a loss of whatever material is being used as a strap corner. Such falling objects create a hazard to both person and property when lost on various roadways or railways.